aldendorff



Aug. 20, 1929. -F. ALDENDORFF 1,725,044

ELECTROMECHANICAL SWITCHING SYSTEM Filed July 28, 1927 4 sheets-sheet 1 7" SLW??? Aug. 20, 1929. F. ALDENDORFF I ELECTROMECHANICAL SWITCHING SYSTEM v4 Sheets-Sheet 2 Filed July 28, 1927 Aug. 20, 1929. F. ALDENDRFF 1,725,044

ELECTROMECHANICAL SWITCHING SYSTEM Filed July 28, 1927 4 Sheets-Sheet 5 l 38a Q24 379 Jnvento'r:

Aug. 20, 1929. F. ALDENDoRl-TF ELEGTROMECHANICAL SWITCHING SYSTEM Filed July 28, 1927 bh @mi Patented Aug. 20, i929.

riesen rarest lorries.

FRITZ ALDNDORFF, ,OF BERLIN,IGERMANY; CHARLOTTE ALDENDORFF WIDOW AND SOLE EEIR 0F SAID'FRITZ ALDENDORFF, DECEASED.

ELECTROMECHANICAL SWITCHING SYSTEM.

Application filed July 26, 1927, Serial No. 209,147, and in Great Britain September 29, 1926.

This invention relates in general to electromechanical or remotely controlled switching systems and more particularly to power driven systems for interconnecting circuits or lines such as telephone lines.

In cial-controlled power driven switching systems employed hitherto it has been necessary to store the dial impulse in a register and to effect the control of the power driven switches with the aid of the impulse storing register. A feature of the present invention is that the connecting operations of switches whose brush driving power is derived from a driving shaft that is separate from the brush carrier of the switches, are controlled by the dial impulses without the aid of an impulse storing register. A further feature of the invention is an electromechanical dial-controlled switching system in which the power for driving the switches is derived from a motor shaft or shafts and brushes of numerical switches operated in unison with the impulses generated by a dial. Another feature of the invention is a dial-controlled step by-step telephone system in which the switch driving power is derived from a power shaft common to a plurality of switches. A further feature of the invention is an electromechanical, dial-controlled, register-less, selecting system in which the brush carrier of a switch is coupled to a driving shaft whenever theI switch is taken into use. A further feature of the invention consists in an electromechanically selecting system in which the brush driving member of a switch is Icoupled and uncoupled from a driving shaft by a mechanically shifted member or members. The brushes of a switch may be stopped on any determined set of contacts by a brush arresting magnet and means controlled by said magnets are provided for applyi '1g power from a driving shaft (which may be common to a number of switches) to the brush carrier. Yet another vfeature of the invention is an electromechanical dial-controlled telephone system in which the power for 'driving the brushes of the conversational switches is derived from driving shafting that is com monto a plurality of switches and the brushes are stopped on the bank contacts of lines or circuits by detents: that cooperate with toothed members that move with the brush carriers Another feature of the. invention is an electromechanical dial-controlled switchin system in which` the switch driving power is derived from a power shaft or shafts and the switch brushes are set onto definite (waiting or wanted) bank contacts by brush setting impulsesthat are generated by dials at the calling station and sent into the brush setting magnets of the switches. Yet another feature of the invention is a multi-position switch having a brush driving member in the form of a rotatable and longitudinally movable screw-thread or worm. Other features of the invention will appear hereinafter.

The invention is illustrated by way of eX- ample in the accompanying drawings.

In the drawings F ig. l is a front View of a part of a selector rack bearing five selectors I, II, III, IV, V.

Fig. 2 is a top view of a selector.

Fig. 8 is a top view' of details of a group selector or connector'.

Fig. 4 is a side view of an arresting member shown in Fig. 3 which is provided for the purpose of increasing the certainty with which the brushes of a selector are stopped in their normal position after the selector has been used.

Fig. 5 shows the manner in which a speed rregula-tor is fitted in a selector.

Fig. 6 shows the circuits of a line finder and Fig. 7 the circuits of trunk finders constructed in accordance with the invention.

Fig. 8 shows the circuits of a group selector and Fig. 9 the circuits of a yconnector constructedin accordance with the invention for telephone exchanges.

Aconsisting of a ring 6 fixed on the shaft 2 a loose bevel cog wheel 7 which is held against longitudinal movement7 a longitudinally movable coupling member 8 splined on the common shaft 2 and a helical spring 9. The bevel wheel 7 has a ring projection provided with radial pins or teeth l0, 1l adapted to be seized by the pin 12 of the longitudinally movable coupling member 8. The bevel 7 only rot-ates when it is coupled to the shaft 2 by the coupling member 8. It is in mesh with the bevel wheel 13 of its associated selector. The wheel 13 is fixed to the right end of a horizontal shaft 14 which is supported in bearings 15, 16 fixed to the selector frame 55. A worm 17 is longitudinally movable but not rotatable with respect to the shaft 14. r1`he worm 17 engages with a worm wheel 19 that is fixed on the selector shaft 20. Also fixed on the selector shaft 2O is a brush arresting wheel 21 with whose teeth a detent- 22 cooperates that is adjustably fixed upon an electromagnet armature 23 pivoted on a fulcrum 24. As long as the electromagnet 25 is notenergized the armature 23 with its detent 22 is held by the spring 26 in the position shown in which the detent 22 is located in a gap between teeth of the arresting 4wheel 21.

Fixed on the shaft 20 are set-s of electrically insulated brushes which are adapted to wipe over bank contacts such as 29, 30, 31, 32,

y etc., Fig. 2. The detent 22 can be adjusted with respect to the armature 23 and the wheel 21 by a screw 34 which engages with an internal thread in a projection 35 of an armature and a similar thread in a bent up end 36 of the detent 22. By this means a ne adjustment of the brushes 27, 28 can be e'ected relatively to the bank contacts in the direction of rotation ofthe brushes. VA coarse adjustment of the bank contacts with respect to the brushes'inay be effected by means of the screws 37 38 which extend through slots in the ends of an arcuate contact bank carrier on Awhich the contact bank is fixed by screws that pass through the acuate layers of bakelite or the like in which the bank contacts are embedded. When the brushes 27 'or 28 are s et onto any set of bank contacts electromagnet 25 is energized the armature 23 is attracted and the detent 22 is moved away from the wheel 21. A helical spring 18 threaded onto the shaft 14 and located between the disc shaped end 39 of the worm 17 and the bearing 16 of the shaft 14, now pushes the worm 17 towards the left and the worm wheel 19 with the shaft20, the brush sets 27, 28', the arresting wheel 21 and the worm wheel 40 of the speed governor are now rotated clockwise (Fig. 2) until the electromagnet 35 is deenergized so that the spring 26 throws the detent 22 into engagement with the arresting wheel 21. 1n order to effect the great est possible rapidity of engagement of the detent 22 with the wheel 21 a comparatively strong spring 26 is employed whose tension canbe regulated by a screw 41. The screw 41 fits into a thread in an angular projection 42 ofthe iron of the field structure of the electromagnet 25. The detaining action on the detent is quickened also by the reaction of a condenser connected to the magnet as shown hereinafter in Figs. 6 to 9.

As soon as the worm 17 is shifted towards the left by the spring 18 a bell crank lever 43 whose lower end presses against the disc 39 of the worm and which is pivoted on a fulcrum 44, lets the coupling member 8 yield to the force of a spring 9 so that it slides downwardly on the common drivingl shaft 2 and its pin 12 engages with one of the pins or teeth 10, 11 of the bevel wheel 7 so that the latter is rotated by the shaft 2 and rotates the bevel wheel 13 and shaft 14 on which the latter is fixed. vWhen the brush shaft 20 is arrested by the detent22 the thrust exerted by the worm 19 on the worm wheel results in the worm 17 which is now being rotated by the shaft 14, being shifted towards the right (Fig. 2) until the spring 18 is fully compressed. When the spring 18 is tensioned in this manner the arm 45 of the bell crank lever-43 will have shifted the coupling ment ber 8 on the common shaft 2 to such an extent that the coupling between the coupling member 8 and the bevel wheel 7 is dissolved and the bevel wheels 7 and 13 and all the other parts of the selectors are restored to their po sitions of rest. j Y

To regulate the speed of the selector brushes7 a speed regulator' is provided which consists of a worm wheel 40 fixed to the shaft 20, a worm 46 engaged by the worm wheel 40, a shaft 47, friction members 48, 49 that are attached to the ends of springs 51. 52 anda cup 50. The shaft 47 is journalled in parts 53, 54 that project forwardly and rearwardly from the selector frame 55. `When the shaft 20 is rotated the wormwheel 40 rotates the worm 46 at a high speed and the friction blocks 48, 49 are then caused by centrifugal force to rub against the internal wall of the cup 50. The active length of the springs 51, 52 can be adjusted by shifting the ring 56.

The selector construction described in the preceding paragraphs is the construction employed for selectors without any particular normal position such as line finders, preselectors, call distributors etc. The saine construction may be employed for numerical switches such as group selectors and connectors, but

Yto increase the certainty with which the ses lector brushes are stopped at a definite zero or normal position when they are restored after use, an additional arresting member 57 may be arranged in accordance with the invention of the selector frame 55. The right end of this arresting member 57 is pivoted on of the safety arresting member 57 drops into vthesat'ety arresting meinoer 5 a hole 61 of the arresting Wheel 21 so as to stop the latter and the brushes. At the same time lor immediately afterwards the Wheel 21 is also engaged by the detent 22 et the detracted armature 23 ot the electromagnet The Worm 17 is new caused to shi'it tov. ards the right on the shaft 14 due to the rotation of the latter until it is unceupled 'from the common driving shaft 2, Shortly before the Worm 17 reaches its extreme r' dit position its disc 39 slips under the proj downwardly extending projec latter out of the hele 61 of tee iviieels 21, s that the Wheel can be turned by the spring; 1 and Worm 17 in a clockwise direction when the magnet 25 is energized again on the selector being taken inte use.

As Will appear from the olloivifig description all the setting movements et the b of a selector are eitected by a single eiu magnet 25. The selector may be employed as a preselector, line finder, call distributor, register or translator, group selector', connector etc.

rEhe switching operation 'which occurs in the connection of a calling line with a wanted line Will new be described with the aid et Figs. G, 7, 8 and 9. 1n 0 the setting' magnet 125 is the brush setting` magnet a line finder Which corresponds to the magnet 25 of Fig. 2.

ln Fig. 7 the setting magnets et cit'- ferent trunk inders are denoted by 225, 22

In Figs. 8 and 9 the setting magnets which correspondte the setting magnet 125 of Fig. 2 are denoted by 325 and 481.

1t Will be assumed that the station or subscriber S desires a connection and te this end raises his receiver. The line relay 100 is then energized by a current which tlows trein the negative pole through the lett Winding ot the line relay 100, 101., 102, S, 103, 1041, r' Winding of 100 to the positive pele. rEhe line rela-y 100 closesits contacts 105, 106 and opens its contacts 107, 108. At contact 105 a vveal; exciting circuit for the starting relay 110 is closed through resistance 109 which causes the starting relay to close its Contact 111. This relay closes its contact 112 also only When tivo or more calls happen simultaneously Whereby the starting relay 110 also receives current through an additional resistance 109', or resistances.

By the closure ot Contact 111 the selector magnet 125 of the line finder equipped With brushes 113 to 116 is energized in a circuit that extends from the negative pole through 125, 117, brush 120, 111, brush 119 ot the trunk finder, brush 11G et the line finder, bank Contact like 123 on which the brush 116 is resting, Contact like 108 oit the line relay of the line on which the brushes et the line finder are set, to the positive pole. lllhen the magnet 125 is thus energized its closes at its contact 124 a circuit that is independent of the contact 111 and withdraws the detent (22, Fig. A2) from the arresting Wheel (21, Fig. 2) of the line tinder se that the driving spring (18, Fig. 2) drives the brushes 113 to 118 arounc. at a high speed until the brush 116 reaches the banlr contact 123 et the calling line which is disconnected from the positive pole by the opening oit the contact 108. The brush setting magnet 125 is thereby deenergized and its detent arrests the brushes on the calling line. The driving spring` of the line Ender is then retensioned in the manner described above. `When the brushes 113 to 116 are stopped on the bank contact set of the calling line the connection extending relay 126 is energized by a current that flows from the negative pole through armature contact 127 of the brush setting magnet 225 of the trunl finder equipped WithA brushes 119 te 122, 126. brush 115, bank Contact 128, contact 105 of the line relay 100, cut-off relay 129 to the positive pele. The cut-eti relay 129 is thus energized and at contacts 101, 1011 it cuts otf the line relay 100 While closing a looking circuit for itself at its contact 130. rlhe relay 128 simultaneously entends the calling line through its contacts 131, 132 to the group selector Fig. 8 Whose impulse relay 3511 is new energized in a circuit that entends trein the positive pole through the left vrindet 354:, 380, 113, 131, 103, S, 102, 1111, 132, 378, right Winding et 354-. to the positive pole. rilhe impulse relay 354 closes at its Contact 350 a circuit ter the slo*v retractinf ginal relay 357 which is weakly e 'l current that iioivs' from the negatiie pole through 360, resistance 350 te the positive pole and closes the contacts 300. Au ex '1t-ing current ter the connection eX- ten ding relay 126 new flows from the negative pele through 300, 118, 120, 115, 128, 130, 129 to the positive pole and also throrgh 118, 133, 121, brush setting magnet causing this lat ter to open its contact 127 and close its contact 1341, While it simultaneously withdraws its detent (similar to 22.. 2) from the arresting Wheel et the trunl: finder tnat the brushes 119 to 122 et the latter are driven by their driving spring (similar to 18, Fig. 2), until the brushes 121, 122 reach bank contaets that are not connected with the negative pole, i. e. until they reach a trunk that is neither in a busy condition by the closure of its contact 118 nor preselected by the brush 122 and Contact 127 of another trunk finder 119 te 122.

rihe calling line is new connected through to the group selector Fig. 8.

1t' two or more subscribers S call simultaneously the marginal relay 110 is fully energized as described so that it closes its contact 112 in addition to 111. By this means a second trunk nder which has been preselected by the brushes 119 te 122 et the second trunk finder magnet 325 in a circuit which extends from f the negative pole through 360, 361, 374, 372,

curs when the brush 322 reaches a contact 391 or 392 which at this time is not connected with the negative pole. During the motion of the brush 322 from the bank contact 373 to the contacts 391, 392 it wipes over an intermediate contact 393 which is connected through contact 394 of the change-over relay 362 and contact 365 of the release relay 357 to the negative pole so that the magnet 325 receives current from the negative pole through 365, 394, 393, 322, wire 395 until the brush 322 leaves the intermediate contact 392. If the armature of the magnet 325 should fail to relapse fast enough to stop the brushes on the bank contact 391 they will be stopped on the next bank contact 392. The reaction of the condenser 396 on the brush controlling magnet 325 will, however, almost invariably make the armature of the magnet relapse so fast that its detent 313 will seize a tooth of the arresting wheel 21 before the brush 322 passes the first dead bank contact 391.

Un the closure of the armature contact 355 of the line relay that follows the relapse of the armature 360 due to the second selecting impulse the brusl'i-controlling magnet 325 is again energized in a circuit extending from the negative pole through 360, 355, 363, bank Contact 391, or 392, controlling brush 322, magnet 325 to the positive pole. The armature of the magnet now again releases the brush shaft and the brushes advance tocontact 398 or 399, the magnet 325 being held energized during their progress from bank contact 392 to the bank contact 398 by vcurrent iiowing from the negative pole through 365, 394, intermediate Contact 397, brush 322, to the positive pole. On the relapse of the armature 360 due to the third interruption or third selecting impulse the brush controlling magnet 325 receives current in a circuit extending from the negative pole through 360, 361, 364, wire 307, contact 306 of the change-over relay 362, bank contact 398, brush 322, wire 395. 1f the brush 322 has stopped on the bank contact 399 instead of 398, the current through 361, 364, wire 30',7 instead of flowing through the relay contact 306, will pass through the bank contact 399, brush 322 to the magnet 325. The armature of the controlling magnet 322 now again releases the brush shaft and the brushes advance from contact 398 or 399 past the intermediate eontact 300, which is connected through contact 394 and 395 to the positive pole to the contact 301 or 302. On theensuin retraction of the armature 360 the mag-v net 325 receives another impulse in a circuit .negative pole.

extending from the negative pole through 360, 355, 363, wire 308, contact 301, 302, or through contact 302 only, if the brush 322 failed to stop on the contact 301 and only stopped on the second short Contact 302, brush 322, wire 395, magnet 325 to the positive pole. The armature of the magnet 325V now again release the brushes and they advance until the brush 322 reaches contact 304 or 305. The brushes are not set onto a bank contact set 305 whichis next to the third group g3 of sets of bank contacts, or on a bank contact set 304 which is next but one to the first set of bank contacts in the group g3. The three selecting impulses having been set in, the oscillations of the armature 360 cease and the vslow-acting change-over relay 362 allows its armature to drop back. 1f the brushes 322 stopped on the irst contact 304 of the two adjacent bank contacts 304, 305 the brush controlling magnet 325 is energized by current flowing from the negative pole through 309, 304, 322, 325 to the positive pole. This circuit is broken as soon as the brush 322 reaches the bank contact 305, because the connection between the adjacent short contact 304, 305 is now broken by the opening of the relay contact 306. Im mediately the brush 322 reaches the bank Contact 305, the brush controlling magnet 325 is energized through a circuit that initiates the trunk hunting operation of the selector, this circuit extending from the negative pole through 365, 381, 3.76, 310, bank Contact 305, brush 322, magnet 325 to the positive pole. The winding of the magnet 325 is now connected through contact 382 and contact 311 of the change-over relay to the brush 350 and is held energized through a current which flows from the negative pole applied to the test contact 312, 313 etc. by other selectors which have previously seized the corresponding trunks of these Contacts. When the brush 350 reaches a test contact, say 314, that is not connected to the negative pole, the circuit through the brush 350 and contacts 311, 382 for the magnet 325 is .tive pole through a resistance 406, contacts 403, 520 in the next selector ahead, brush 351, contact 338, winding 387, contact 365 to the The relay 371 extends the calling line L through contacts 377, 379 and brushes 352, 353 to the next selector ahead (Fig. 9) and at contact 375 closes a locking circuit for'the release relay 357 that extends from the negative pole through 365,331, 375, resistance 356, 357 to the positive pole.

Another novel feature of 'the group selector is the means for preventing the brushes from passing beyond the select-or group, e. g.

group g3, when all the trunks in the group are engaged. To this end the last test contacts 320, 321, 322 in each group g3, g2, g1 are not multiply connected like the other contacts in the same row, but are lett entirely unconnected so that when the test brush 350 reaches such a contact, the circuit'of the brush controlling magnet 325 will be broken in any case and the brushes thus always stopped on the last trunk. lf this last trunk is busy the test relay 371 will not be sufficiently energized through the resistance (such as 406) in the next selector ahead, and the calling station will not be connected through but will receive a lousy signal. The caller will then replace his receiver and the relays 354, 357 will be deenergized to initiate the restoring operation ot the group selector kwhich has been already described.

When the calling line is extended to the connector the impulse relay 400 is energized by a current flowing from the exchange battery over the calling line and the impulse relay 400 closes its contacts 401, 402 whilst opening its contacts 403, 404. The release relay 405 is then energized by a current flowing through contact 401, 405, resistance 406 and at the same time the change-over relay 408 is short circuited by the connection of the negative pole through contacts 409, 402 through the resistance 407.

It will first be assumed that the calling subscriber desires line No. 11 in the selected 100 group so that a one tens dialling impulse and one units dialling impulse are sent in. When the tens dialling impulse is sent in the impulse relay 400 letsy its armature drop back once and then remains energized for some time. When the armature of 400 drops back the short circuit of the change-over relay 408 is opened at contact 402 so that this relay is'energized by a current that. flows from the negative pole through 409, 408, resistance 407 to the positive pole so that it closes its contact 410, 411, 412, 413, 413 and opens its contacts 414, 415, 415. No further function is brought about by these contacts for the time being, but when vthe impulse relay 400 attracts its armature again, the relay 416 receives a weakly energizing current (negative pole, 409, 402, 410, right winding of 416, contact 418 of test relay 419, resist ance 417, contact 431 of release relay, bank contact 432, brush 437, Contact 444 of relay 416, brush setting magnet 461, positive pole) and closes its Contact 457, 459 but does notshitt its other contacts. The current. that flows through the brush setting magnet 461 is kept so weak by the resistance 417 and the right winding of relay 416 that it does not attract its armature. rhe atoredescribed single tens impulse therefore does not give rise to any motion of the connector brushes 437 to 441 so that the olif-normal switch W remains in its normal position.

The relay 416 keeps its easily moved con-V tacts 457, 459 closed due to a weak excitation caused by a current that flows trom the negative pole through 409, ott-normal contact 642, 457, lett winding of 416, 418, re-

sistance 417, contact 431, bank contact 433,.

brush 438, 445, brush setting magnet 461 to the positive pole.

In the pause which ensues after the tens impulse has been sent in, the change-over relay 408 is deenergized due to its being short circuited by the Contact 402 so that its armature drops back and an exciting circuit for the connecting extending relay 460 is closed at contact 414 which extends from the negative pole through 414, 426, lower winding ot' 460, resistance 472, Contact 459, contact 431, bank contact 432, brush 437, contact 444, magnet 461 to the positive pole. This current through the magnet 461 is only strong enough to energize the connection extending relay 460 which closes its contact 451, 449, 448, 446, 443, 445 and opens its contacts 452, 450, 447, 442, 444. The relay 460 closes a. locking circuit for itself which extends troin the negative pole through 409, 423, 448, lower winding of 460,472, 459, 431, 432, 438, 445, magnet 461 to the positive pole, but does not cause any movement ot the armature of the brush setting magnet to takeV place.

On the units impulse now being sent in by the calling station, the impulse relay 400 by its contact 404 causes an energization ot the brush setting magnet 461 by a current that liows from the negative pole through 409, 404, 459, 431, 432', 438, 445, magnet 461 to the positive pole and urtheri'nore by a transitory opening of its contact 402 the impulse relay 400 opens the short circuit of the changeover relay 408 so that this relay is energized and at its contact 413 closes a weak energizing circuit forthe test relay 419 that extends from the negative pole through 413, 446, winding 420 to the positive pole and results in the closure of the easily moved armature llO contacts429, 430 of the test relay but causes no operation ot its other contacts.

In consequence oit its one excitation the brush setting magnet 461 allows the connector closed but the other contacts ofthe test relay are not operated so that a busy signal current is applied to the Wire 480 that leads to the calling station over the following parts: Busy signal producer 481, contact 415, 429,l 428, 451 The caller hears the busy signal and hangs up the receiver, Whereby the impulse relay 400 is permanently deenergized so as to permanently shortcircuit the release relay 405 by its contact 403. rllhe release relay 405 then closes at its contact 409 a brush restoring circuit Which entends from the negative pole through 409', contact 464 ot the ott"- normal brush, brush setting magnet 461 to the positive pole and remains closed until the connector brushes reach their zero or normal position Where the brush restoring circuit through the brush setting magnet 461 is opened to deenergize this magnet. The latter allows its armature to drop back so that its detent drops into a gap in the brush arresting Wheel and arrests the brushes in their zero position. To increase the certainty with which the brushes are stopped in their normal position at each restoration of the brushes a safety stop like 57 Figs. 3 and 4 can be provided Which engages with the brush arresting Wheel sometime betere the brushes reach their normal position and stops them when they reach this position. Immediately afterwards the said stop 57, 60 is lifted out ot engagement With the arresting l Wheel. by the disk 39, Fig. 2, at the right end ot the driving Worm 17 shortly betere this Worm has completely retensioned the driving spring` 18.

lt will now be assumed that the calling station after being extended to the connector only sends in a single tens impulse and then abandons the connection. ln such a case the single oscillation ot' the armature of the impulse relay 400 which ensues after the calling line has been extended to the connector and the impulse relay 400 and the release relay 405 have been energized, causes the changeoverl relay 408 to be energized and to be deen-ergized shortly afterwards due to its short circuit by the contact 402. `Whilst the changeover relay 408 is still energized the marginal relay 416 is Weakly energized by a current that flows from the negative pole through 409, 402, 410, right Winding ot 416, 418, 417, 431, 432, 437, 444, 461 to the positi e pole. rlthe brush setting magnet 461 is novv energized by this Weak current, but when the calling station hangs up the release relay 405 is deenergized later than the impulse relay and then the brush settting magnet 461 is energized by strong energizing current that flows from the negative pole through 409, 404, 459, 431, 432, 437, 444, 461 to the positive pole. its soon as the selector brushes leave their zer position, the brush setting magnet is kept energized through the o-nornial contact and the Contact 409 of the release relay until tl e brushes reach their zero position in which the energizing current of the magnet 461 is opened at the olli-normal Contact 464.

1t will now be assumed that the calling station abandons the connection after it has been extended to the connector but before it sends in a tens selecting impulse. In such a case the cl an ge-over relay 408 is energized by 'he opening ot its short circuit atcontact 402 during the oscillation ot the armature of the impulse relay Which ensues after the energization ot' the impulse relay 400 and the release relay 405 `at the moment when the Wanted line is connected through. rlhe said energ tion ot the changeover relay 408 is, however, not followed by any further operation. By the short circuiting of the release relay 405 contact 403, this relay is decnergized and then the ch angeover relay 408 is also deenergized by the opening oi its circuit contact 409.

It Will noi-.v be assumed that the calling station selects line No. 35 in the selected hundred.

When the calling line is connected through to the connector the relays 400 and 405 are energized in the manner alreadv described. During the first relapse of the impulse relay armature caused by the iirst tens impulse the change-over relay 408 is also energized in the manner already described and on the ensuing attraction ot the armature of the impulse relay 400 the marginal relay 416 weakly energized. During the relapse ot' the impulse relay armature caused by the second tens impulse the brush setting magnet 461 receives a strong exciting impulse that extends trom the negative pole through 409, 404, 459, 431, 432, 437, 444, magnet 461 to the postive pole. The armature ot the magnet 461 noiv releases the brush carrier and the brushes of the connector are rotated 'forward until the magnet is deenergized. lthis happens when the tens controlling brush 437 reaches the intermediate contact 484 located halt Way to the end ot the first group of ten bank contact sets, because as long as the brush 437 Wipes on the bank contact 483, the magnet 461 is kept energized by a current that flows 'from the negative nolo through Contact 413 ot the change-over relay, bank contact 483, 437, 444, 461 to the positive pole. During the attraction et the armature ot' the impulse relay 400 that corresponds to the second tens impulse the brush controlling magnet 461 receives another energizing impulse that loWs trom the negative pole through 409, 402, 411, 487, 437, 444, 461 to the positive pole. rlhe armature of the brush controlling magnet now remains energized by a` current that flows through 413, 485, 437, 444, 461 and only relapses to stop the brushes when the tens controlling brush 437 reaches the bank contact 486 which at this moment is dead. lt is thus seen that during the oscillation' 'of the impulse relay armature which corresponds to the second tens impulse the selector brushes are forwarded to execute two halt steps oit a long step which brings them up to contact 486.

During the oscillation of the impulse relay caused by the third tens impulse, potential is now applied iirst through 404, 418 to the contacts, 486, 487 and then through 402, 411 to the contacts 489, 489 whereby the magnet 461 is caused to allow the connector brushes to advance first to bank contact 489 and then to bank contact 491. During the wiping ot' the brush 487 along the bank contact 487, the magnet 461 receives current from the negat-ive pole through 409, 404, 487 and while the brush 487 wipes along the contacts 488 and 490 the magnet receives current from the negative pole through 418', 488. The bank contact 491 is the second last bank contact in the second tens group of bank contact set and be't'ore the units impulses come in the brush 487 must be resting upon the last bank contact 492 to be prepared for the unit selecting function. For this reason the magnet 461 receives an impulse during the pause between the tens and units impulses during which the change-over relay 408 relapses. This impulse is independent ot the tens impulses and iiows 'trom the negative pole through 415, 491, 487, 444, 461 to the positive pole and causes the magnet 461 to allow the brushes to advance to contact 492.

The provision of two brush stepping contacts 484, 484 486, 487 489 489 etc. instead of only a single contact between each two adjacent brush advancing contacts like 4.88, 485 485, 486 etc. is made to enhance the certainty with which the brushes that rotated at a high speed are stopped at each stopping position. t the brushes fail to stop at the lirst brush stopping contact they are always sure to stop on the second brush stopping Contact and if at the end of a tens groups ot bank contact set they st-op at the first (491) instead of the second (492) brush stopping conta-ct they are caused to advance as described to the second brush stopping contact 492 when the change over relay 408 relapses at the end of the series of tens impulses in question.

The operations that occur in the setting of the brushes onto line No. 85 in the said 100 have been described up to the point where the brushes are set onto the set ot bank contacts that is located before the lirst bank contact set of the third tens group of bank contact sets.

When the changeover relay 408 relapses the relay 460 is energized by current that flows from the negative pole through 414, 426, bottom winding of relay 460, olf-normal contact 471 to the positive pole. The relay 460 closes a locking` circuit for itseli for the time being which extends from the negative pole armature that corresponds tothe Erst units impulse the commutating relay 465 is energized by a current that iiows 'from the negative pole through 409, 404, 494, 466, left winding of relay 465, wire 495, bankcontact 496, units controlling brush 488, 445, brush setting magnet 461 to the positive pole. The current in this circuit, due to t'he resistance of the winding of the commutatiug relay, is too weak to energize the magnet ,461. The coinmutating relay 465 lirst closes at contact 467 a locking circuit for itselt that extends from the negative pole through 418, 467, left wind ing of 465 and winding of magnet 461, which latter is now connected through contact 469 to the Contact 402 of the impulse relay. llhen the closure of the contact 402 of the impulse relay 400 that corresponds to the iirst units impulse is eillected, the magnet 461 receives current directly from the negative pole through 409, 402, 469, 495, 496, 488 so that it attracts its armature and allows the brushes to advance to the next units control Contact e 497 which at this moment is not connected to the battery. The commutating .relay 465 now keeps itself energized during the closure of the contact 402 of the impulse relay, but during the relapse oi the impulse relay that corresponds to the second units impulse, the comn'iutating relay 465 is deenergized so that at the attraction of the armature of the impulse relay 400 that corresponds to the sec# ond units impulse the magnet 461 is again fully energized by current that flows from the negative pole through 409, 402, 494, 470, 501, 497, 488, 448, 461 to the positive pole and causes the brushes of the connector to be advanced to the bank Contact 498. In this manner the connector brushes are caused to advance one step during each to and fro movement ot the impulse relay armature so that the brushes rest yon the bank Contact sets of line No. 85 after the fifth units impulse.

it is to be noted that the windings of the commutating relay are arranged to counteract together so that the armature of the commutating relay is not held by current that may liow from the positive pole to its rightwinding contact 467, left winding 467, 418 to the negative pole.

lVhen the brushes have been sent onto lthe bank contact set oi' the desired line of the manner described and a certain time after the sending in ot the units impulses have relapsed, the change-over relay drops back and applies a test potential to the top winding of lthe test relay 419 over the following part:

negative pole, 14, 430, top winding of relay 419. If t-he selected line is busy no strengthening of the excitation of the test relay takes place so that it does not operate any of its contacts in addition to its contacts 429, 430 which were previously closed. A. busy signal current is then applied to the wire 480 over the following part: busy signal producer 481, 415, 429, 428, 451, 480. The alternating busy signal current passes through the condenser 510 to the calling station where it produces an audible signal. The calling station then hangs up, where the impulse relay 400 is deenergized and the connector is restored to its zero or normal position in the manner already described.

If the selected line is free the test relay 419 is strongly energized by the application of the test potential to its top winding as described and it closes its contact 422, 424, 418, 427 while opening its contacts 423, 418, 426, 428. By the closure of the contact 422 a busy potential is applied with the test contacts of the selected line. By the closure of the contacts 424 the resistance 417 is cut out of the circuit of the relay 416 whose previously closed weak locking circuit (negative pole, 409, 462, 467 or negative pole 412, 457, left winding of 416, 418, resistance 417, 431, 432, 438, 445, 461, positive pole) was opened when the brush 438 left the first bank contact 432', so that a new circuit by which the relay 416 is fully energized is prepared which is closed by contact 443 of relay 460 when the selected subscriber responds. At contact 426 the locking circuit of relay 460 i'sY opened before the contact 424 is closed. At contact 428 the busy signal current is cut off. At contacts 425, 427 the ringing current is appliedto the selecting subscriber, this current flowing periodically from the ringing current machine 511 through the common ringing interrupter and the common condenser 513 and through 433, 452, 427, brush 451, selected subscribers station back to the other brush 440, 425, 447, common condenser 515 to earth. In the intervals between the ringing currents, the exchange battery is applied through the common interrupter 516 and the relay 460 to theselected line (516, 415, top winding of n460, 426, 441', wanted station, 440, 418, lower winding of 460, 471, positive pole), When the wanted station responds, the relay 460 is energized and at its contacts 451, 448 connects the calling station through to the selected station.Y At the same time the relay 460 closes at its contact 443 a strong exciting circuit for the back release and switching relay 416 that extends from the negative pole through 409, 422, 443, right winding of 416, 424 to the positive pole.

The relay 416 closes a locking circuitifor itself that extends from the negative pole through 463, 454, right winding of 416, 458 to the positive pole.

TWhen the selected subscriber hangs up at the end of the conversation, the release 405 is deenergized by a short circuit that is formed by the direct connection of the negative pole to the right end of the winding of the release relay 405 in the following Inanner: negative pole, 409, 422, 442, 456. The release relay at its contact 409 now opens the locking circuit of the test relay 419 so that its armature relapses. At contact 409 the release relay closes a restoring circuit for the connector magnet 461 which now releases the connector brushes and, if they are not previously stopped by a mechanical stop like 57, Figs. 3, 4, arrests them again in their zero position where the magnet 461.is deenergized 457, right winding of 416, 458, positive pole) of the relay 416 is opened.

`By the aforesaid short circuiting ofthe winding 405 of the release relay, this relay is only partly deenergized. It is maintained slightly energized by a second winding 522 due to a current that flows from the positive pole through 522, 521, brush 351 of the group selector 388, 387, 365 to the negative pole. Although this current is sucient to keep the contact 521 of the release relay of the connector energized, it does not sufiice to hold any of the contacts of the test relay 371 of the group selector in their operated position so that the contacts of this relay relapse whereby the release relay 357 is deenergized bythe opening of the contact 375. The deenergization of the relay 357 results in the restoration of the group selector, Fig. 8, in the manner already described and by the opening of its contact 365 the winding 522 of the release relay in the connector is also deprived of current so that the release relay of the connector now opens its contact 521 and closes its contact 520. All the parts ofthe group selector and connector are now restored The brushes of the line finder motor individual to each brush carrier or by a driving shaft which is common to the brush carriers of the group of selectors or to all the switches in the exchange.

A motor which is common to all the switches or to a group of them may be arranged to be started only whenever a switch driving worm 17 leaves its normal position The motor may also drive all the signalling devices such as a ringing current generator, a busy signal producer, ringing current interrupter etc.

l. In combinati-on, a subscribers line, an impulse transmitter for sending impulses over said line, a plurality of switches for extending said line, each switch including a A brush carrier adapted to execute steps of different lengths, a constantly rotating drive shaft, a spring for storing energy from said drive shaft, a brush setting magnet for releasing the stored energy to allow said carrier to be operated in synchronism with the impulses transmitted over the line.

3. In an automatic switch, a brush carrier, means for moving said carrier in steps of different lengths comprising a constantly rotating power shaft, a screw threaded coupling member, means for coupling said member to said shaft to move said member and said carrier together, means for positively arresting the movement of said carrier and for thereupon causing said screw threaded member to be moved ina reverse direction, and a. spring member for storing energy due to the reverse movement of said screw threaded member.

4. In an automatic switch, a brush carrier, a constantly rotating power shaft, a spring for controlling the initial movement of said carrier, a screw threaded member for controlling the subsequent movement of said carrier independently of said spring, means responsive to the initial movement of said carrier for coupling said screw threaded member to said shaft, means for positively arresting said carrier to reverse the direction of movement of said screw threaded member whereby said carrier is uncoupled from said shaft.

5. In an automatic switch, a rotating power shaft, a brush carrier normally uncoupled from said shaft, means for coupling said carrier to said shaft, means for positively arresting said carrier while .said shaft is rotating, and means responsive to said arresting for uncoupling the carrier from the shaft.

6, .In an automatic switch, a constantly rotating power shaft, a brush carrier, means for coupling said carrier to said shaft including a member adapted to be moved in one direction with said carrier under control of said shaft, means for causing a reverse movement of said member independently of the movement of the carrier and a spring adapted to be tensioned by the reverse movement of said member for uncoupling said carrier from said shaft.

7. An automatic switch, a brush carrier adapted to execute steps of different lengths, an electrome'chanically controlled detent for arresting said carrier in an advance position, means comprising a constantly rotating power shaft and a spring storing means for advancing said carrier and for restoring said carrier to normal position. i

8. An automatic switch `comprising a brusl carrier, a rotary power shaft, means for coupling said carrier to said shaft to cause said carrier to execute continuous steps of different lengths, and a magnet for positively arresting the carrier at the end of each step.

Y 9. An automatic switch comprising a brush carrier, a power shaft, means for coupling said shaft to said carrier to allow said car.- rier to execute steps of different lengths, a brush'controlling magnet for 'controlling the lengths of said steps and for allowing said carrier to be restored to normal under control 4of said shaft, a mechanical detent for stopping said carrier in its normal position.

l0. In an automatic switch, a brush carrier, a power shaft, means comprising a worm drivingmember for 'coupling said shaft to said carrier to allow said carrier to execute steps of different lengths, a brush controlling magnet for controlling the lengths of'said steps and for allowing said carrier to be restored to normal under control of said shaft, a mechanical detent for stopping said carrier in its normal position, said mechanical detent being adapted to be moved from its brush stopping position by said worm driving member. V

11. In combination, an automatic switch having a brush carrier, a constant speed power shaft, means for coupling said shaft to said carrier and a regulator for controlling the speed of said carrier while it is coupled to said shaft.

12. In combination,` an automatic switch having a brush carrier, a constant speed power shaft, means comprising .a screw threaded member and a spring for couplingV 13. In an automatic switch, a brush carrier, a constantly operating power shaft for said carrier, means for coupling said carrier to said shaft, means comprising a spring for giving said carrier a preliminary movement and for effecting the coupling of said shaft in carrier whereby said carrier is rotated from said shaft independently of said spring.

14. In an automatic switch, a brush carrier, a constantly operating power shaft, means comprising a screw threaded member for advancing said carrier from normal position under control of the power from said shaft, and means for advancing said carrier to normal position comprising a spring which is tensioned only after said carrier has been in an advance position away from normal.

15. In a power driven switch, power driven brushes that respond in continuous motions to impulses in the rhythm in which they are sent from an impulse producer, a brush stopping arrangement by which the brushes are held between bank contact groups in any one of a plurality of positions, and a correcting arrangement for moving the brushes from any incorrect position to a correct position for an ensuing selecting operation.

16. In a switch to whose wipers a torque is applied which moves them in long steps in response to liberations of the wiper shaft performed by the armature of an electro-magnet that receives current impulses through contacts whose positions indicate the points of the switch bank at which the wipers are to be arrested, a s-et of said indicating contacts at the beginning and another set at approximately the middle of each long step around the contact bank, circuit arrangements for applying potential to said sets of indicating contacts alternately in accordance with dialling impulses sent to the switch whereby the wipers are liberated so that they execute long steps, and further circuit arrangements by which the said electromagnet receives an impulse to cause it to allow the wipers to move to the last contact of a set of indicating contacts located at the beginning of a long step whenever they have been stopped at the end of a dialling operation on an indicating contact located before the last one of the set.

17. In a power driven selector, sets of bank contacts distributed in the contact bank, a brush driven over said sets of bank contacts and other contacts placed between said sets, a brush stopping magnet whose circuit is controlled by said brush and said contacts, and means for causing said brush to move from any bank contact of a set on which it may have stopped to the last contact of said set when a pause ensues between series of numerical impulses that affect said stopping magnet.

18. In a power driven selector, sets of bank contacts distributed in the contact bank, a brush driven over said sets of bank contacts and other contacts placed between said sets, a brush stopping magnet whose circuit is controlled by said brush and said contacts, and a further brush through which, when a pause ensues between series of numerical impulses, said stopping magnet is energized to allow the selector' brushes to move from any position in which they may have stopped to a position in which they are ready to respond correctly to the neXt series of numerical impulses.

19. In a high speed switch for automatic telephone systems, a brush carrier, a constantly operating power shaft, means for transmitting power from said shaft to said carrier comprising a worm wheel fastened to said carrier, a slidable and rotatable worm cooperating with the worm on said wheel, means for positively arresting said carrier while it is effectively coupled to said shaft, said slidable worm serving when the carrier is arrested to store energy from said shaft to be used for driving the carrier for a subsequent movement thereof.

In testimony whereof I have axed my signature.

FRITZ ALDENDORFF. 

